Check in here Thursday morning to read about the city airport system's involvement in an international web of companies tied to city officials. Texas Watchdog will probe previously unrevealed financial activities of the airport system.

The story will show:

-- The Houston Airport System is intertwined with a network of nonprofit and for-profit companies, including companies incorporated in the British Virgin Islands, Ecuador and Costa Rica with a revolving set of key players that includes city officials.

-- The companies work almost entirely in secret despite being created by, and for, a government entity and using public resources. Indeed, this web of companies -- including a nonprofit signed off on by the Houston City Council and run by city airport officials -- says its books aren't open to anyone, even the city, and it's resisting efforts to make its records public.

-- This web of companies is linked to tens of millions of dollars in loans by overseas banks, the federal government and the World Bank, while largely escaping public scrutiny here at home. In fact, one line of credit linked to the airport system's hidden network of companies tops out at $200 million, and it's refusing to release documentation showing whether Houston taxpayers are on the hook for any of that amount.

Texas Watchdog began looking at the Houston Airport System after the abrupt resignation of its director, Richard Vacar, in May. Vacar and Mayor Bill White have refused to say specifically why Vacar left.